#define _CRT_SECURE_NO_WARNINGS  1
#include<iostream>

using namespace std;

//class stu
//{
//public:
//	
//
//private:
//	char name[10];
//	int age;
//	char gender[5];
//	int num;
//}
//

namespace lv_left
{
	void Swap(int& a, int& b)
	{
		int tmp = a;
		a = b;
		b = tmp;
	}
	void Swap(int& a, double& b)
	{
		double tmp = b;
		b = a;
		a = tmp;
	}
	int ReturnSize(int& a)
	{
		return sizeof(a);
	}
	int ReturnSize(double& a)
	{
		return sizeof(a);
	}

	
}

int main()
{
	cout << "Hello World!" << endl;
	int a = 12;
	int b = 21;
	cout << a << '/' << b << endl;
	lv_left::Swap(a, b);
	cout << a << '/' << b << endl;

	int c = 12;
	double d = 3.14;
	cout << c << '/' << d << endl;
	lv_left::Swap(c, d);
	cout << c << '/' << d << endl;

	cout << lv_left::ReturnSize(c) << endl;
	cout << lv_left::ReturnSize(d) << endl;


	return 0;
}